In this paper, we review the role of the
norpA-encoded phospholipase C in light and thermal entrainment of the circadian clock in
Drosophila melanogaster. We extend our discussion to the role of
norpA in the thermo-sensitive splicing of the
per 3′ UTR
[...] Read more.
In this paper, we review the role of the
norpA-encoded phospholipase C in light and thermal entrainment of the circadian clock in
Drosophila melanogaster. We extend our discussion to the role of
norpA in the thermo-sensitive splicing of the
per 3′ UTR, which has significant implications for seasonal adaptations of circadian behaviour. We use the
norpA mutant-generated enhancement of
per splicing and the corresponding advance that it produces in the morning (M) and evening (E) locomotor component to dissect out the neurons that are contributing to this
norpA phenotype using GAL4/UAS. We initially confirmed, by immunocytochemistry and
in situ hybridisation in adult brains, that
norpA expression is mostly concentrated in the eyes, but we were unable to unequivocally reveal
norpA expression in the canonical clock cells using these methods. In larval brains, we did see some evidence for co-expression of NORPA with PDF in clock neurons. Nevertheless, downregulation of
norpA in clock neurons did generate behavioural advances in adults, with the eyes playing a significant role in the
norpA seasonal phenotype at high temperatures, whereas the more dorsally located CRYPTOCHROME-positive clock neurons are the likely candidates for generating the
norpA behavioural effects in the cold. We further show that knockdown of the related
plc21C encoded phospholipase in clock neurons does not alter
per splicing nor generate any of the behavioural advances seen with
norpA. Our results with downregulating
norpA and
plc21C implicate the rhodopsins Rh2/Rh3/Rh4 in the eyes as mediating
per 3′ UTR splicing at higher temperatures and indicate that the CRY-positive LNds, also known as ‘evening’ cells are likely mediating the low-temperature seasonal effects on behaviour via altering
per 3′UTR splicing.
Full article
